RP Max Gear in a Manual Transmission

[MolaKule]

Our MT transmission lubes were rated GL4/GL5 because they contained EP additives that provided GL5 protection, but at the same time
the additive pack did not affect soft metals.

You can do this with the proper mix of base oils and selected additives.

 

[SR77]

Thanks Molekule,
So if I understand this right, most of the time if a bottle states both GL4 and GL5, it has been tested to meet the GL5 rating but doesn't have the percentage of additives in it that a straight GL5 has which also makes it compatible for GL4 applications too? So for example Coastal which states both GL4 & GL5, even though this is rated as a GL5 oil, it would be safe to use in transmissions that require a GL4 for yellow metals because it has both ratings on the bottle and has less of the harmful additives then a straight GL5?

 

[aquariuscsm]

Originally Posted By: SR77
Thanks Molekule,
So if I understand this right, most of the time if a bottle states both GL4 and GL5, it has been tested to meet the GL5 rating but doesn't have the percentage of additives in it that a straight GL5 has which also makes it compatible for GL4 applications too? So for example Coastal which states both GL4 & GL5, even though this is rated as a GL5 oil, it would be safe to use in transmissions that require a GL4 for yellow metals because it has both ratings on the bottle and has less of the harmful additives then a straight GL5?



Me,I just prefer to keep a GL4 only oil in the manual transmission and a GL5 only oil in the rear diff. The GL4/5 mix oil has always scared me off a bit. I may be paranoid,but it seems you`d have to maybe compromise the quality of either/or oil to have a "mixed" rating. I`d rather keep "transmission only" fluid in the transmission,and "diff only" fluid in the diff.

 

[MolaKule]

Quote:
it has been tested to meet the GL5 rating but doesn't have the percentage of additives in it that a straight GL5 has which also makes it compatible for GL4 applications too? So for example Coastal which states both GL4 & GL5, even though this is rated as a GL5 oil, it would be safe to use in transmissions that require a GL4 for yellow metals because it has both ratings on the bottle and has less of the harmful additives then a straight GL5?


Forget about the percentage of additives.

A dual rated GL5/GL4 has the right TYPE of additives and base oil combination that can give you the GL5 protection rating yet it would be safe for metals other than steel.

A differential gear oil will not kill your manual transmission but it is NOT the corrrect oil for a manual transmission.

The point I have trying to make is this: Just because a differential lube is rated soley for GL4 or dual rated for GL5/GL4, doesn't mean it is the best oil for your manual transmission. Again, a manual transmission lube is designed with the right viscosity and additive combo for the MT.

Quote:
Manual Transmission fluids use a different friction modifier for synchro engagement, a modifier that does NOT contain the same chemicals as differential lubes.

Differential lubes use friction modifiers to reduce mechanical and fluid friction and add some anti-shudder friction modifier for limited slip, both very different chemical compounds.

Manual Transmission fluids use a different friction modifier for synchro engagement, a modifier that does NOT contain the same chemical compounds as do differential lubes.

Both lubes contain the same type of EP additives, just in different strengths, different additive types, or additive ratios.

Most manual transmission "specific" fluids (GL4) contain about 40% to 60% of the EP additive of differential lubes (GL5) with inactive or buffered sulphurs. GL4 has come to infer a gear lube with the above percentages of EP additive. The exception of course is ATF fluid used in some of the newer transmissions.

You also have to consider the viscosity of the fluid that the transmission was designed for. The spectrum now ranges from ATF to 75W90 viscosities.

Ever since the synchromesh-type fluids appeared on the scene (such as the GM Synchromesh fluid), drivers have had better shifting due to better synchro engagement, attributed to the specialized friction modifier used in these lubes. This specialized friction modifier is better for metallic and composite synchros in terms of shifting and life.

A diffy 75W90 (GL5) usually has a higher viscosity than does an mtl in the same advertized weight.

So a differential lube may not kill your transmission, but it is not the optimum lube.

 

[D-Roc]

Made a BIG difference in my Dodge 3500 w/ G56...

 

[D-Roc]

I'll never use anything else now.

 

[Leo]

Take it for what its worth but the RP Max gear did quite poorly when it came to the copper corrosion test in the Amsoil White Paper.

 

[aquariuscsm]

Amsoil MTG HANDS DOWN! You absolutely have to try this stuff. It`s simply amazing!

 

[Pablo]

Originally Posted By: aquariuscsm
Amsoil MTG HANDS DOWN! You absolutely have to try this stuff. It`s simply amazing!

Glad it worked out.

P

 

[D-Roc]

Originally Posted By: Leo
Take it for what its worth but the RP Max gear did quite poorly when it came to the copper corrosion test in the Amsoil White Paper.


It probably did, I have no doubt about it. But this is why I went with the RPS
"APPLICATIONS
Recommended for automotive and light truck applications that require synchromesh transmission fluid. Applications include manual transmissions and transaxles such as New Venture NV T350, NV 1500, NV 2550, NV 3500, NV 3550, NV 5600, and Tremec T4, T5, T18, T56, T176, TKO500, TKO600, TR 3450 and TR 3550. Replaces MTF-94 fluid for Land Rover, MG, and Mini Cooper. Replaces Honda Genuine MTF fluid for manual transaxles and Texaco MTX fluid. Not for use in engines or wet clutch applications."

I see nothing anywhere there where it states that MTL is made specifically for applications where ATF is called for. RPS does. SO, as far as I can see, the RPS was made with this in mind. Important for me, as my transmission is specd for atf.
Naturally, I also expect all products which are not amsoil to not do as well as amsoil in amsoil's tests....

 

[Johnny]

You left out this part of the Amsoil spec.

Synthetic Manual Synchromesh
Transmission Fluid (MTF)
SAE 5w30

Specifications include:

Specifications
• GM 9985648
• GM 9986105
• GM 9985535
• Chrysler MS-9224
• Chrysler MS-9417

Part Numbers
• GM 12345349 or 12345577
• GM 12377916
• GM 1052931
• Chrysler 4874464
• Chrysler 4874465

None of these spec/part numbers call for ATF, but a synchromesh fluid, which is what this product was made/designed for. Not for automatic transmissions.

For manual transmissions that require/spec ATF, Amsoil makes a great ATF that works great.

 

[D-Roc]

Originally Posted By: Johnny
You left out this part of the Amsoil spec.

Synthetic Manual Synchromesh
Transmission Fluid (MTF)
SAE 5w30

Specifications include:

Specifications
• GM 9985648
• GM 9986105
• GM 9985535
• Chrysler MS-9224
• Chrysler MS-9417

Part Numbers
• GM 12345349 or 12345577
• GM 12377916
• GM 1052931
• Chrysler 4874464
• Chrysler 4874465

None of these spec/part numbers call for ATF, but a synchromesh fluid, which is what this product was made/designed for. Not for automatic transmissions.

For manual transmissions that require/spec ATF, Amsoil makes a great ATF that works great.



Yeah, and I tried the Amsoil ATF in my transmission and although better than the Mopar brand atf, it was nowhere near the performance and smoothness of the RPS. You're also right about the MTL being deigned for applications requiring a synchromesh fluid, but in my case I am quite pleased with the RPS and how it has performed. Royal Purple has designed that fluid as a synchromesh fluid as well.
"Synchromax is recommended for manual transmissions that specify an automotive transmission fluid. It’s also ideal for 4×4 transfer cases and motorcycle gear boxes. Synchromax is fully compatible with all types of friction materials. It provides excellent corrosion and oxidation protection without affecting the soft metals commonly found in manual transmission synchronizers."

In this particular instance, the only reason I used RPS is to see out of curiosity...I had tried three or four different fluids and non met my expectations. It's pretty common with many Dodge Diesel w/g56 to experience minor notchiness. Some have it, others claim it is the smoothest shifting transmission they have had in their diesel truck. SO, it worked for me. A guy I have spoken to on another forum said the same thing about his Ford Mustang. He used atf for a while before trying RPS and was quite happy with it. It's not for everyone.
If Amsoil ATF provided the performance I have been looking for, I would be using that. At this point, up to the point of when I installed RPS I wasn't brand loyal...I am now- at leastfor my transmission.

 

[D-Roc]

Oops, just noticed the thread was initially about max gear...my fault. I was referring to the synchromax. My mistake.

 

[gtx510]

Originally Posted By: MolaKule
2. I know of no one who recommends diffy fluid in a manual transmission; diffy lubes don't have the right viscosites nor the correct friction modifiers.

Unless the transaxle uses separate gear oil for the diff, I think all the companies/cars below use GL-5 in their transaxles. I'm sure there's a couple that I'm forgetting.
Subaru
Porsche
Ford GT
some Audi's
Ferrari
De Tomaso
Lambo

 

[gtx510]

Originally Posted By: MolaKule
Our MT transmission lubes were rated GL4/GL5 because they contained EP additives that provided GL5 protection, but at the same time
the additive pack did not affect soft metals.

You can do this with the proper mix of base oils and selected additives.

And don't these GL-5's usually get a MT-1 rating??

 

[Jimbo]

There is a misunderstanding about the MT-1 rating, it is only for heavy duty truck and bus transmissions, not passenger cars and pickups. Those big-rig transmissions are not sycnronized, as far as I know, so there are no issues with friction modification or yellow metal corrosion.